buf.c revision 1590 
1/*
2 * Copyright (c) 1988, 1989, 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 * Copyright (c) 1989 by Berkeley Softworks
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Adam de Boor.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 *    must display the following acknowledgement:
20 *	This product includes software developed by the University of
21 *	California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39#ifndef lint
40static char sccsid[] = "@(#)buf.c	8.1 (Berkeley) 6/6/93";
41#endif /* not lint */
42
43/*-
44 * buf.c --
45 *	Functions for automatically-expanded buffers.
46 */
47
48#include    "sprite.h"
49#include    "make.h"
50#include    "buf.h"
51
52#ifndef max
53#define max(a,b)  ((a) > (b) ? (a) : (b))
54#endif
55
56/*
57 * BufExpand --
58 * 	Expand the given buffer to hold the given number of additional
59 *	bytes.
60 *	Makes sure there's room for an extra NULL byte at the end of the
61 *	buffer in case it holds a string.
62 */
63#define BufExpand(bp,nb) \
64 	if (bp->left < (nb)+1) {\
65	    int newSize = (bp)->size + max((nb)+1,BUF_ADD_INC); \
66	    Byte  *newBuf = (Byte *) realloc((bp)->buffer, newSize); \
67	    \
68	    (bp)->inPtr = newBuf + ((bp)->inPtr - (bp)->buffer); \
69	    (bp)->outPtr = newBuf + ((bp)->outPtr - (bp)->buffer);\
70	    (bp)->buffer = newBuf;\
71	    (bp)->size = newSize;\
72	    (bp)->left = newSize - ((bp)->inPtr - (bp)->buffer);\
73	}
74
75#define BUF_DEF_SIZE	256 	/* Default buffer size */
76#define BUF_ADD_INC	256 	/* Expansion increment when Adding */
77#define BUF_UNGET_INC	16  	/* Expansion increment when Ungetting */
78
79/*-
80 *-----------------------------------------------------------------------
81 * Buf_OvAddByte --
82 *	Add a single byte to the buffer.  left is zero or negative.
83 *
84 * Results:
85 *	None.
86 *
87 * Side Effects:
88 *	The buffer may be expanded.
89 *
90 *-----------------------------------------------------------------------
91 */
92void
93Buf_OvAddByte (bp, byte)
94    register Buffer bp;
95    int    byte;
96{
97
98    bp->left = 0;
99    BufExpand (bp, 1);
100
101    *bp->inPtr++ = byte;
102    bp->left--;
103
104    /*
105     * Null-terminate
106     */
107    *bp->inPtr = 0;
108}
109
110/*-
111 *-----------------------------------------------------------------------
112 * Buf_AddBytes --
113 *	Add a number of bytes to the buffer.
114 *
115 * Results:
116 *	None.
117 *
118 * Side Effects:
119 *	Guess what?
120 *
121 *-----------------------------------------------------------------------
122 */
123void
124Buf_AddBytes (bp, numBytes, bytesPtr)
125    register Buffer bp;
126    int	    numBytes;
127    Byte    *bytesPtr;
128{
129
130    BufExpand (bp, numBytes);
131
132    memcpy (bp->inPtr, bytesPtr, numBytes);
133    bp->inPtr += numBytes;
134    bp->left -= numBytes;
135
136    /*
137     * Null-terminate
138     */
139    *bp->inPtr = 0;
140}
141
142/*-
143 *-----------------------------------------------------------------------
144 * Buf_UngetByte --
145 *	Place the byte back at the beginning of the buffer.
146 *
147 * Results:
148 *	SUCCESS if the byte was added ok. FAILURE if not.
149 *
150 * Side Effects:
151 *	The byte is stuffed in the buffer and outPtr is decremented.
152 *
153 *-----------------------------------------------------------------------
154 */
155void
156Buf_UngetByte (bp, byte)
157    register Buffer bp;
158    int    byte;
159{
160
161    if (bp->outPtr != bp->buffer) {
162	bp->outPtr--;
163	*bp->outPtr = byte;
164    } else if (bp->outPtr == bp->inPtr) {
165	*bp->inPtr = byte;
166	bp->inPtr++;
167	bp->left--;
168	*bp->inPtr = 0;
169    } else {
170	/*
171	 * Yech. have to expand the buffer to stuff this thing in.
172	 * We use a different expansion constant because people don't
173	 * usually push back many bytes when they're doing it a byte at
174	 * a time...
175	 */
176	int 	  numBytes = bp->inPtr - bp->outPtr;
177	Byte	  *newBuf;
178
179	newBuf = (Byte *)emalloc(bp->size + BUF_UNGET_INC);
180	memcpy ((char *)(newBuf+BUF_UNGET_INC), (char *)bp->outPtr, numBytes+1);
181	bp->outPtr = newBuf + BUF_UNGET_INC;
182	bp->inPtr = bp->outPtr + numBytes;
183	free ((char *)bp->buffer);
184	bp->buffer = newBuf;
185	bp->size += BUF_UNGET_INC;
186	bp->left = bp->size - (bp->inPtr - bp->buffer);
187	bp->outPtr -= 1;
188	*bp->outPtr = byte;
189    }
190}
191
192/*-
193 *-----------------------------------------------------------------------
194 * Buf_UngetBytes --
195 *	Push back a series of bytes at the beginning of the buffer.
196 *
197 * Results:
198 *	None.
199 *
200 * Side Effects:
201 *	outPtr is decremented and the bytes copied into the buffer.
202 *
203 *-----------------------------------------------------------------------
204 */
205void
206Buf_UngetBytes (bp, numBytes, bytesPtr)
207    register Buffer bp;
208    int	    numBytes;
209    Byte    *bytesPtr;
210{
211
212    if (bp->outPtr - bp->buffer >= numBytes) {
213	bp->outPtr -= numBytes;
214	memcpy (bp->outPtr, bytesPtr, numBytes);
215    } else if (bp->outPtr == bp->inPtr) {
216	Buf_AddBytes (bp, numBytes, bytesPtr);
217    } else {
218	int 	  curNumBytes = bp->inPtr - bp->outPtr;
219	Byte	  *newBuf;
220	int 	  newBytes = max(numBytes,BUF_UNGET_INC);
221
222	newBuf = (Byte *)emalloc (bp->size + newBytes);
223	memcpy((char *)(newBuf+newBytes), (char *)bp->outPtr, curNumBytes+1);
224	bp->outPtr = newBuf + newBytes;
225	bp->inPtr = bp->outPtr + curNumBytes;
226	free ((char *)bp->buffer);
227	bp->buffer = newBuf;
228	bp->size += newBytes;
229	bp->left = bp->size - (bp->inPtr - bp->buffer);
230	bp->outPtr -= numBytes;
231	memcpy ((char *)bp->outPtr, (char *)bytesPtr, numBytes);
232    }
233}
234
235/*-
236 *-----------------------------------------------------------------------
237 * Buf_GetByte --
238 *	Return the next byte from the buffer. Actually returns an integer.
239 *
240 * Results:
241 *	Returns BUF_ERROR if there's no byte in the buffer, or the byte
242 *	itself if there is one.
243 *
244 * Side Effects:
245 *	outPtr is incremented and both outPtr and inPtr will be reset if
246 *	the buffer is emptied.
247 *
248 *-----------------------------------------------------------------------
249 */
250int
251Buf_GetByte (bp)
252    register Buffer bp;
253{
254    int	    res;
255
256    if (bp->inPtr == bp->outPtr) {
257	return (BUF_ERROR);
258    } else {
259	res = (int) *bp->outPtr;
260	bp->outPtr += 1;
261	if (bp->outPtr == bp->inPtr) {
262	    bp->outPtr = bp->inPtr = bp->buffer;
263	    bp->left = bp->size;
264	    *bp->inPtr = 0;
265	}
266	return (res);
267    }
268}
269
270/*-
271 *-----------------------------------------------------------------------
272 * Buf_GetBytes --
273 *	Extract a number of bytes from the buffer.
274 *
275 * Results:
276 *	The number of bytes gotten.
277 *
278 * Side Effects:
279 *	The passed array is overwritten.
280 *
281 *-----------------------------------------------------------------------
282 */
283int
284Buf_GetBytes (bp, numBytes, bytesPtr)
285    register Buffer bp;
286    int	    numBytes;
287    Byte    *bytesPtr;
288{
289
290    if (bp->inPtr - bp->outPtr < numBytes) {
291	numBytes = bp->inPtr - bp->outPtr;
292    }
293    memcpy (bytesPtr, bp->outPtr, numBytes);
294    bp->outPtr += numBytes;
295
296    if (bp->outPtr == bp->inPtr) {
297	bp->outPtr = bp->inPtr = bp->buffer;
298	bp->left = bp->size;
299	*bp->inPtr = 0;
300    }
301    return (numBytes);
302}
303
304/*-
305 *-----------------------------------------------------------------------
306 * Buf_GetAll --
307 *	Get all the available data at once.
308 *
309 * Results:
310 *	A pointer to the data and the number of bytes available.
311 *
312 * Side Effects:
313 *	None.
314 *
315 *-----------------------------------------------------------------------
316 */
317Byte *
318Buf_GetAll (bp, numBytesPtr)
319    register Buffer bp;
320    int	    *numBytesPtr;
321{
322
323    if (numBytesPtr != (int *)NULL) {
324	*numBytesPtr = bp->inPtr - bp->outPtr;
325    }
326
327    return (bp->outPtr);
328}
329
330/*-
331 *-----------------------------------------------------------------------
332 * Buf_Discard --
333 *	Throw away bytes in a buffer.
334 *
335 * Results:
336 *	None.
337 *
338 * Side Effects:
339 *	The bytes are discarded.
340 *
341 *-----------------------------------------------------------------------
342 */
343void
344Buf_Discard (bp, numBytes)
345    register Buffer bp;
346    int	    numBytes;
347{
348
349    if (bp->inPtr - bp->outPtr <= numBytes) {
350	bp->inPtr = bp->outPtr = bp->buffer;
351	bp->left = bp->size;
352	*bp->inPtr = 0;
353    } else {
354	bp->outPtr += numBytes;
355    }
356}
357
358/*-
359 *-----------------------------------------------------------------------
360 * Buf_Size --
361 *	Returns the number of bytes in the given buffer. Doesn't include
362 *	the null-terminating byte.
363 *
364 * Results:
365 *	The number of bytes.
366 *
367 * Side Effects:
368 *	None.
369 *
370 *-----------------------------------------------------------------------
371 */
372int
373Buf_Size (buf)
374    Buffer  buf;
375{
376    return (buf->inPtr - buf->outPtr);
377}
378
379/*-
380 *-----------------------------------------------------------------------
381 * Buf_Init --
382 *	Initialize a buffer. If no initial size is given, a reasonable
383 *	default is used.
384 *
385 * Results:
386 *	A buffer to be given to other functions in this library.
387 *
388 * Side Effects:
389 *	The buffer is created, the space allocated and pointers
390 *	initialized.
391 *
392 *-----------------------------------------------------------------------
393 */
394Buffer
395Buf_Init (size)
396    int	    size; 	/* Initial size for the buffer */
397{
398    Buffer bp;	  	/* New Buffer */
399
400    bp = (Buffer)emalloc(sizeof(*bp));
401
402    if (size <= 0) {
403	size = BUF_DEF_SIZE;
404    }
405    bp->left = bp->size = size;
406    bp->buffer = (Byte *)emalloc(size);
407    bp->inPtr = bp->outPtr = bp->buffer;
408    *bp->inPtr = 0;
409
410    return (bp);
411}
412
413/*-
414 *-----------------------------------------------------------------------
415 * Buf_Destroy --
416 *	Nuke a buffer and all its resources.
417 *
418 * Results:
419 *	None.
420 *
421 * Side Effects:
422 *	The buffer is freed.
423 *
424 *-----------------------------------------------------------------------
425 */
426void
427Buf_Destroy (buf, freeData)
428    Buffer  buf;  	/* Buffer to destroy */
429    Boolean freeData;	/* TRUE if the data should be destroyed as well */
430{
431
432    if (freeData) {
433	free ((char *)buf->buffer);
434    }
435    free ((char *)buf);
436}
437